Antiinflammatory benzimidazole derivative with inhibitory effects on neutrophil function.

5-Methyl-2,2,2-trifluoroethylsulfonyl-1H-benzimidazole (BI-L-45 XX) inhibits both neutrophil enzyme release and chemotaxis in vitro and also inhibits chemotaxis in vivo. BI-L-45 XX has an IC50 between 16 microM and 25 microM in inhibiting lysosomal enzyme release from human peripheral blood neutrophils. In a Boyden chamber experiment, BI-L-45 XX inhibited migration in response to fMLP with an IC50 of 5 microM. When given orally to passively sensitized rats at doses of 0.1 to 1.0 mg/kg, it inhibited migration of neutrophils to the pleural cavity in response to an antigen (ovalbumin) challenge. BI-L-45 XX also shows activity in the developing adjuvant arthritis model, with an ED50 of 45 mg/kg, while exhibiting no significant inhibition of cyclooxygenase in a human platelet assay. This suggests the possibility that its antiinflammatory activity may be in part mediated by its effect on neutrophil function.

4-(Indolyl-3)-1-(benzimidazolonylalkyl)-piperidines, a novel group of potential antiallergy compounds.

A group of indolyl-benzimidazolone-piperidines is described and the structure-activity with reference to the passive cutaneous anaphylaxis (PCA) in rats is discussed. Compound 7b, 4-(indolyl-3)-1-(benzimidazolonyl-propyl)-piperidine, which has the highest potency in this test, was studied in more detail with regard to antihistaminic and secretory cell stabilization properties.

In vivo secretion of 3 alpha-hydroxy-5 alpha-pregnan-20-one, a potent anaesthetic steroid, by the adrenal gland of the rat.

3 alpha OH-5 alpha-Pregnan-20-one (allo-THP), a steroid with strong anaesthetic properties, was found to be secreted by the adrenal gland of the rat in quantities similar to those secreted by the rat ovary. From the hypnotic potencies established for this and other endogenous steroids there can be little doubt that the total amount of steroids with anaesthetic properties produced in a female rat are sufficient to exert a depressant action on certain cells of the brain. In rats with intact adrenal glands a positive correlation existed between the adrenal secretion of allo-THP and pregnenolone or progesterone, whereas that between allo-THP and DOC was negative. This could be the result of a competition between the enzymes responsible for the oxidation and reduction of progesterone, the common precursor of allo-THP and DOC. The possibility that allo-THP could have hypotensive actions was suggested.

N-(4-substituted-thiazolyl)oxamic acid derivatives, a new series of potent, orally active antiallergy agents.

A series of N-(4-substituted-thiazolyl)oxamic acid derivatives were synthesized and tested for antiallergy activity in the rat PCA model. These compounds were conveniently prepared by treatment of the appropriate acetophenone with thiourea and iodine or by reaction of the chloroacetylbenzene with thiourea to give the corresponding aminothiazoles; subsequent condensation with ethyloxalyl chloride gave the thiazolyloxamates. Many of the analogues showed a 50% inhibition at less than 2 mg/kg po or less than 0.4 mg/kg iv and were significantly more potent than disodium cromoglycate, which in the rat PCA model is orally inactive and gives a 50% inhibition at 1.2 mg/kg iv. Hydrolysis of the oxamates generally resulted in enhanced activities, while substitution of the phenyl ring with a variety of substituents (e.g., 4-F, 4-OEt, and 4-NHCOCH3) did not significantly enhance the activity of the unsubstituted phenyl derivative. One of the ethanolamine salts, N-[4-(1,4-benzodioxan-6-yl)-2-thiazolyl]oxamic acid ethanolamine salt (61, PRH-836-EA), has been selected for further pharmacological evaluation.

Salvage of circulating pyrimidine nucleosides in the rat.

A new procedure was developed to measure uridine and cytidine in plasma. These nucleosides are present in micromolar concentrations in the plasma of rats, mice, and humans. Inhibitors of pyrimidine synthesis de novo (pyrazofurin or N-phosphonacetyl-L-aspartate) produce only modest decreases in the concentration of circulating uridine or cytidine in the rat. Since both uridine and cytidine are rapidly cleared from the circulation of the rat, constant infusions of radiolabeled uridine and cytidine were used to establish a steady-state specific activity of circulating nucleoside without altering the normal endogenous concentration. These studies permitted an estimation of the contribution of circulating pyrimidine nucleoside to the nucleotide pools of various rat tissues. Most of the uridine entering the circulation (greater than 70%) is catabolized rather than salvaged by formation of nucleotides. Cytidine in the circulation is much more efficiently utilized and is predominantly salvaged. The implication of these results for chemotherapy based on inhibition of pyrimidine synthesis de novo is discussed.

Hypertensive action of 18-hydroxydeoxycorticosterone.

18-Hydroxydeoxycorticosterone is an adrenal steroid hormone causing salt and water retention and is secreted in greatly increased amounts in response to the pituitary hormone adrenocorticotropic hormone. Its production is abnormally high in some forms of hypertension in man and rat. Direct proof that 18-hydroxydeoxycorticosterone is capable of causing hypertension is present. Daily subcutaneous injections of 200 micrograms, a low physiological dose, significantly increase the blood pressure of unilaterally nephrectomized saline-treated rats after 2 weeks. This strengthens the hypothesis that 18-hydroxydeoxycorticosterone contributes to the etiology of hypertension, possibly by a mechanism involving stressinduced release of adrenocorticotropic hormone.